Barrel wall thickness

[Craig Budgeon]

Drew my understanding of Britsh proof is that a 12 ga. exceeding nominal size (.729) by more than 010" has to be reproofed before the gun can be sold in England and is marked 12/1 on the barrel flats after successful reproof. Based on that understanding Gibbs would sell a gun with a bore of .735 and is still in proof by .004. Ed Good there would be many Parkers left in dealers gun racks if .030 minimum was the accepted number.

[Drew Hause]

That is correct Craig pre-1954.
1954-1989 the bore would be marked in inches, but I have seen some also marked with the 12/1.

[Craig Budgeon]

Drew, 12/1 can mean reproof, the gun was originally built with barrels which exceeded .739 dia., or that the gun had been rebarreled which is common in England.

[Drew Hause]

Correct, 12/1 = .740" - .750"; if rebarreled prior to 1954
The flats would carry the Crown over R if re-proved.

Interesting collection of proof marks. Originally proved 35-36 by 'P' on the upside-down date code, with '12' and '13/1' (.719" - .728") bore
Then reproved 1959 and marked .729"



J. Blanch & Sons original London Proof 1887-1896 with bore 12 (.729-.739").
The time bomb damascus barrels Birmingham re-proved (tiny Crowned R) 1999 (BD) with bore 18.7 mm = .736" which could have been the original bore